Feeds, pump-arounds, and refluxes to distillation, absorption, quench and wash towers are commonly introduced by pipe distributors. Most of the known pipe distributors include openings (e.g., slots or holes) to spread out the liquid containing-jets issuing from the openings. A typical example is depicted in U.S. Pat. No. 5,014,740 in which a plurality of jets are arranged along a distributor pipe at various angles to ensure wide distribution. Alternatively, a pipe distributor may also include openings that release a fluid against an impingement wall to spread out the fluid stream. An exemplary configuration is depicted in U.S. Pat. No. 4,855,089, in which the impingement wall may additionally include a corrugated portion for lateral distribution of the fluid.
Where the incoming fluid consists of both liquid and gas, jets are typically directed against a vertical or inclined wall, typically the wall of a downcomer or an impingement baffle, which is often placed a short distance away from the openings (wherein the openings usually point at an angle towards the wall). Thus, the wall spreads up the jets, and if the jets contain gas, the wall also separates the up-flowing gas from the down-flowing liquid.
In order to achieve even distribution of the introduced fluid, the velocity of the fluid exiting the holes or slots in the pipe distributors within the tower must generally be about 2-3 times greater than the fluid velocity in the pipe. This requires either using high hole (or slot) velocities or low pipe velocities. High hole velocities are often undesirable, as they tend to lead to excessive splashing, turbulence and entrainment. On the other hand, low pipe velocities are also often undesirable because they lead to expensive nozzle and internal piping requirements, which may interfere with other tower internals (e.g., trays).
Consequently, many known pipe distributor configurations are based on a compromise in which hole (or slot) velocity is substantially identical with pipe velocity. Unfortunately, such configurations typically exhibit significantly adverse distribution characteristics. Most significantly, the horizontal momentum in the direction of flow inside the pipe persists as the fluid exits the pipe, thus resulting in relatively high flows towards the end of the pipe and low flows near the beginning of the pipe. The relatively high liquid flow towards the end of the pipe leads to maldistribution in the unit (e.g., distillation tray beneath the pipe distributor) that receives the liquid.
Therefore, although there are numerous pipe distributor configurations and methods are known in the art, all or almost all of them suffer from one or more disadvantages. Consequently, there is still a need to provide improved configurations and methods for pipe distributors.